opencv（NoneAPI100例---1）--红蓝颜色通道交

Mat channel_swap(cv::Mat img) 

{

    // get height and width

    int width = img.cols;

    int height = img.rows;

    // prepare output

    cv::Mat out = cv::Mat::zeros(height, width, CV_8UC3);

    // each y, x

    for (int y = 0; y < height; y++) 

    {

        for (int x = 0; x < width; x++) {

            // R -> B

            out.at<cv::Vec3b>(y, x)[0] = img.at<cv::Vec3b>(y, x)[2];

            // B -> R

            out.at<cv::Vec3b>(y, x)[2] = img.at<cv::Vec3b>(y, x)[0];

            // G -> G

            out.at<cv::Vec3b>(y, x)[1] = img.at<cv::Vec3b>(y, x)[1];

            }

    }

        return out;

}

cv::Mat img = cv::imread("D:/chat.png", cv::IMREAD_COLOR);

cv::imshow("old", img);

// channel swap

cv::Mat out = channel_swap(img);

//cv::imwrite("out.jpg", out);

cv::imshow("sample", out);

cv::waitKey(0);